A 49-year-old man presents to his physician for a routine examination and is found to be hypertensive. He has no past medical history, and his family history is unknown since he was adopted. Blood work shows a BUN and creatinine of 21 mg/dL and 1.6 mg/dL, respectively. Abdominal ultrasound shows bilaterally enlarged kidneys with many cysts.
Which of the following is NOT a potential complication of this disease?
Renal cell carcinoma. Autosomal dominant polycystic kidney disease (ADPKD) is caused by a mutation in the PKD1 (more common) or PKD2 genes and causes progressive renal disease starting most commonly in the fourth decade. There is usually a positive family history, so many patients are diagnosed early with a screening ultrasound (or other imaging modality) that shows multiple large cysts in both kidneys. (D) Hepatic and pancreatic cysts can also develop. (A) Any cause of renal failure will produce hypertension. Treatment with ACE inhibitors or ARBs, along with control of hypertension, can slow down the progression of the disease but there is no cure for the disease. (C) The most concerning extrarenal complication of ADPKD is cerebral aneurysms, which can rupture and cause intracerebral or subarachnoid hemorrhage. (E) Valvular disease is also very common in these patients, especially mitral valve prolapse and aortic regurgitation. (B) Pancreatic cysts may slightly increase the risk of certain types of pancreatic cancer, but ADPKD is not associated with an increased risk of renal cell carcinoma.
A 58-year-old woman is referred to an ophthalmologist because of vision loss. She describes previous episodes of acute vision impairment that gradually improved over days. An image of her retina is shown in Figure below.
If this patient were to undergo renal biopsy, what are the pathologic findings associated with this disease?
Nodular glomerulosclerosis, mesangial expansion, and basement membrane thickening. Although it is unlikely that the Medicine shelf examination will require interpretation of fundoscopic images, this question makes a few important points about diabetes. First, diabetic retinopathy is extremely common and is a major cause of blindness. There are proliferative (neovascularization of the retina) and nonproliferative forms, with common features of microaneurysms, flame hemorrhages, dot–blot hemorrhages, soft exudates (“cotton wool spots”), and macular edema. There is a large amount of hard exudates seen in the image above, which is caused by the leakage and deposition of lipid and protein from the retinal vessels. Some diabetic patients with advanced ophthalmologic findings will have diabetic nephropathy; however, retinopathy often precedes nephropathy, so that diagnosis of diabetic retinopathy with a simple fundoscopic examination can herald the onset of other microvascular complications. The correct answer to the question is identifying the three pathologic features of diabetic nephropathy, which is answer choice A. Nodular glomerulosclerosis lesions are also referred to as Kimmelstiel–Wilson lesions.
(B) These findings are seen in RPGN, with causes including granulomatosis with polyangiitis, microscopic polyangiitis, and Goodpasture syndrome. (C) These are the pathologic findings of hypertensive nephrosclerosis, another very common cause of CKD. (D) Subepithelial immune complex deposits are seen in poststreptococcal glomerulonephritis.
A 62-year-old woman presents to the Emergency Department after experiencing gross hematuria and passing several blood clots in the urine. She denies any abdominal pain. Eventually a cystoscopy is performed, which confirms the suspected diagnosis of urothelial cancer of the bladder.
Which of the following is the most important risk factor for this condition?
Smoking. Transitional cell (urothelial) bladder cancer is the most common urinary tract cancer, and smoking accounts for approximately half of the cases. If ever in doubt, smoking is always a good answer on the shelf examination. (B, C) There are many occupational exposures that increase the risk of bladder cancer, such as benzene, aniline dyes, diesel fumes, and so forth. (D) Anything that causes chronic inflammation of the urothelium will increase the risk of bladder cancer, but not to the degree that smoking does. Other important risk factors for malignancies of the urinary tract include a history of gross hematuria, analgesic abuse, radiation, and cyclophosphamide.
A 59-year-old woman presents to the Emergency Department complaining of severely painful skin lesions in the abdomen and thighs. Her medical history is significant for hypertension, hyperlipidemia, and end-stage renal disease. She has an arteriovenous fistula and undergoes hemodialysis 3 times weekly. She denies any recent medication changes or any illicit drug abuse, and denies ever taking warfarin. She is afebrile with a blood pressure of 162/96 mmHg and a heart rate of 96 beats per minute. On physical examination, there are areas of livedo reticularis over the abdomen with subcutaneous nodules and several necrotic ulcerations with eschar on both thighs (Figure below). Her distal pulses are 2+ in all four extremities.
A review of her laboratory records over the past few months shows an uptrending calcium-phosphate product.
Which of the following is the most likely diagnosis?
: Calcific uremic arteriolopathy. Also known as calciphylaxis, calcific uremic arteriolopathy is a devastating complication of end-stage renal disease (although it can rarely occur in patients without renal disease). Though there is vascular calcification that occurs in every patient with endstage renal disease, calcific uremic arteriolopathy is a separate process that portends a poor prognosis. There is debate over the exact pathophysiology, but it is associated with an increased or uptrending calcium-phosphate product (serum calcium × serum phosphate), elevated PTH, and high vitamin D doses. A skin biopsy confirms the diagnosis and shows medial calcification and subintimal fibrosis without any evidence of a vasculitis. (Note: important electrolyte and metabolic disturbances in end-stage renal disease include hyperkalemia, hypocalcemia, hyperphosphatemia, metabolic acidosis, secondary hyperparathyroidism that can progress to tertiary hyperparathyroidism, and renal osteodystrophy.)
(A) Henoch–Schönlein purpura is a small-vessel vasculitis that presents with palpable purpura of the lower extremities and buttocks, abdominal pain, hematuria, and arthralgias. The patient’s lesions are necrotic, and the vignette does not suggest hematuria or arthralgias. (C) Necrotizing fasciitis would present with fever, a rapidly expanding and erythematous lesion, and possibly local crepitation of the skin. (D) The onset of deep venous thrombosis is typically not symmetric, and would not cause necrotizing skin lesions. (E) Nephrogenic systemic fibrosis typically occurs after exposure to gadolinium contrast in patients with renal failure. The fibrotic skin lesions progress distally to proximally, leading to a “woody” appearance of the skin. Early calcific uremic arteriolopathy may resemble nephrogenic systemic fibrosis, but not after the necrotic ulcers develop.
A 29-year-old man with no significant medical history complains of tea-colored urine. He reports that he “just got over a cold.” He denies any current fever, weight loss, flank pain, abdominal pain, or new sexual contacts. These symptoms have occurred twice before and have selfresolved without any treatment. He is afebrile with normal vitals, and his examination is unremarkable. Laboratory tests are drawn, which show a BUN of 14 mg/dL and a creatinine of 1.1 mg/dL. A urinalysis shows 2+ blood.
Which of the following is the most appropriate next step in management?
Observation. IgA nephropathy (Berger disease) is the most common cause of primary glomerulonephritis in the developed world. The most common clinical presentation is recurrent gross hematuria that follows an upper respiratory tract infection, although many patients have microscopic hematuria ± proteinuria that is discovered on routine urinalysis. On histology, there is deposition of IgA in the mesangium and glomerular capillary wall on immunofluorescence. The course of the disease is typically slow; half of patients will progress to end-stage renal disease over >20 years’ time. However, IgA nephropathy may be associated with other glomerular diseases and some patients may develop RPGN. (D) Renal biopsy is used to confirm the diagnosis, but not all patients require biopsy. A biopsy may be useful if the patient has significant proteinuria, AKI (elevated creatinine), or hypertension. Patients without these findings like the one in this vignette can be observed without treatment and do not require renal biopsy. Repeat urine studies should be performed in 6 to 12 months. (B) If the patient developed significant proteinuria, then an ACE inhibitor or ARB would be useful to decrease the proteinuria and slow down the progression of the disease. (C) Corticosteroids may be used in patients with more severe disease.
Click to expand